A 30-year-old man is brought to the emergency department due to left-sided weakness. His left arm was sluggish after awakening, and he had difficulty walking to the bathroom. The patient has no known medical conditions but has a 2-month history of positional dyspnea. Vital signs are within normal limits. On examination, strength of the left upper and left lower extremity is reduced, and touch/temperature sensation is similarly diminished. Cardiovascular examination reveals an intermittent murmur at the apex without carotid bruits. Echocardiography shows a mobile, 3-cm left atrial mass obstructing the mitral opening during diastole. Histologic examination of this mass would most likely show which of the following findings?

Question

A 30-year-old man is brought to the emergency department due to left-sided weakness.  His left arm was sluggish after awakening, and he had difficulty walking to the bathroom.  The patient has no known medical conditions but has a 2-month history of positional dyspnea.  Vital signs are within normal limits.  On examination, strength of the left upper and left lower extremity is reduced, and touch/temperature sensation is similarly diminished.  Cardiovascular examination reveals an intermittent murmur at the apex without carotid bruits.  Echocardiography shows a mobile, 3-cm left atrial mass obstructing the mitral opening during diastole.  Histologic examination of this mass would most likely show which of the following findings?

Quizplus · Accepted Answer

11ec160b_38c2_93df_9249_1738bc38eb1d_MD0001_00 This patient's left atrial mass on echocardiography is consistent with an atrial myxoma; this benign tumor is the most common primary cardiac neoplasm. Approximately 80% originate in the left atrium, and they can present with systemic embolization (eg, stroke, as in this patient) from tumor fragments passing into the systemic circulation. The tumors may also lead to constitutional symptoms (eg, fatigue, weight loss, low-grade fever) resulting from cytokine release, and they may cause transient mitral valve obstruction, leading to symptoms that can mimic mitral valve stenosis (eg, dyspnea, hemoptysis). Physical examination often reveals an intermittent or positional mid-diastolic murmur ("tumor plop") that results from the motion of the tumor mass obstructing the mitral valve orifice. Histopathologic examination of a myxoma reveals amorphous extracellular matrix with scattered stellate or globular myxoma cells within abundant mucopolysaccharide (myxoid) ground substance containing chondroitin sulfate and hyaluronic acid. Because of their high vascularity, these tumors often demonstrate areas of hemorrhage accompanied by brown, hemosiderin-laden macrophages. (Choices B and C) Primary malignant cardiac tumors are quite rare; those that occur are usually either sarcomas or lymphomas. Malignant vascular spindle cells suggest primary cardiac angiosarcoma, which usually arises in the right atrium and is exceedingly rare. Malignant epithelial cells with necrotic debris suggest secondary involvement of the heart from a metastatic malignancy (eg, melanoma, lung cancer, breast cancer). Metastatic spread to the heart usually involves the pericardium and rarely creates a mobile intracardiac mass. (Choice D) An organized thrombus can form in the left atrium or left atrial appendage in patients with atrial flutter or fibrillation and may cause stroke due to systemic embolization. However, thrombi are typically adherent to the cardiac endothelium; a mobile mass in the left atrium is more characteristic of a myxoma. (Choice E) Lipomas are benign tumors composed of well-organized, mature adipocytes. They are the second most common type of primary cardiac neoplasm; however, unlike myxomas, lipomas rarely embolize. Educational objective: Myxomas are the most common primary cardiac neoplasm, and approximately 80% originate in the left atrium. Patients may have systemic embolization (eg, stroke) or symptomatic mitral valve obstruction that may be worse with certain body positions. Histopathologic examination reveals amorphous extracellular matrix with scattered stellate or globular myxoma cells within abundant mucopolysaccharide ground substance. __________ References: Cardiac myxomas: 24 years of experience in 49 patients. (http://www.ncbi.nlm.nih.gov/pubmed/12467822)

A 30-Year-Old Man Is Brought to the Emergency Department Due